TW201402259A - Solder alloy - Google Patents

Abstract

Provided is an Sn-Zn-based solder alloy which is capable of reducing the amount of generated dross even when the solder alloy in a molten state is exposed to the atmosphere, suppressing color change or reoxidation of the molten solder alloy, and suppressing the occurrence of a chipping phenomenon of Al and Ni. The solder alloy has an alloy composition consisting of, in terms of mass%, 3-25% of Zn, 0.002-0.25% of Ti, 0.002-0.25% of Al and the balance being Sn so that an oxide film is formed preferentially to Zn on the surface of a solder bath to suppress the diffusion of Al and Ni in the solder alloy.

Description

Soft solder alloy

This invention relates to solder alloys. In particular, it relates to a solder alloy which can suppress scum generated during soldering and suppress the occurrence of ablation of Al or Ni plating of the object to be bonded.

Conventionally, electric wires used in wire sets of automobiles, motor terminals or circuit wirings used for electrochemical products, etc., have been gradually used as conductive materials. In recent years, automobiles and electrochemical products have been continuously required to be lightweight, and Cu (specific gravity: 8.9) used in these has been gradually replaced by Al (specific gravity: 2.7) having a specific gravity of about 1/3 of Cu.

A method of welding such an Al electric wire, an Al terminal, an Al wiring, or the like (hereinafter, referred to as "Al member" as appropriate) is, for example, a fusion welding method such as a dipping method or a flow method. In the immersion method, the end portion of the Al electric wire or the Al terminal is immersed in a soldering groove of the stationary groove to perform welding. In the flow mode, the jet welding material of the jet flow tank is brought into contact with the Al wiring for welding. In the welding methods, the molten welding materials of the stationary tank and the jet flow tank are exposed to the atmosphere for a long time.

However, in the past, it has been soft for the purpose of welding Al components. Welding alloys have always used Sn-Zn solder alloys. This is because the electrode potential difference between Zn and Al is small to suppress electrolytic corrosion. As shown in JIS Z 3281, the Sn-Zn solder alloy has, for example, a low melting point of Sn-9Zn, Sn-15Zn, and Sn-20Zn.

Further, Patent Document 1 discloses a Sn-Zn-based solder alloy containing Ti and Al, and is a solder alloy which can directly weld a hard-to-weld metal having an oxide film such as Al.

Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-326088

However, the Sn-Zn solder alloy can suppress the corrosion of Al. However, because of the high activity of Zn, it reacts with oxygen in the atmosphere, and when it is used in the dipping mode or the flow mode, the liquid level of the soldering groove occurs in a large amount. scum. This scum not only impairs the appearance of the soft solder joint, but also removes the Al member before immersion, resulting in deterioration of workability. In addition, the consumption of solder alloys surges and leads to an increase in cost due to the occurrence of a large amount of scum.

On the other hand, the solder alloy disclosed in Patent Document 1 contains Ti or Al. These elements are elements which are easily oxidized, and are elements added for the purpose of improving the wettability of an oxide such as glass or ceramic to improve the joint strength.

However, as for the welding of the oxide, as described in the embodiment of Patent Document 1, each ultrasonic cleaning requires removal of foreign matter on the surface of the glass plate. welding. The solder alloy disclosed in Patent Document 1 directly performs welding on Al. However, in essence, the oxide film on the surface of Al is welded, and the solder alloy is not exposed to the atmosphere in a molten state for a long time. . Therefore, in Patent Document 1, there is no problem that scum occurs in the liquid surface of the solder bath.

Further, Patent Document 1 has conducted a review for the purpose of improving the bonding strength with an oxide. The element used in the solder alloy does not form an intermetallic compound when it is bonded to the element on the surface of the oxide. Therefore, when welding, there is no occurrence of oxide seizure.

Here, even if scum occurs, it is also possible to use the bonding of Al as long as the scum is removed from the liquid surface of the molten solder alloy. However, the appearance of the welded Al may be impaired if the molten solder alloy is discolored or the oxide is regenerated after the scum is removed and before the Al is joined.

Further, in order to suppress surface oxidation of Al or the like, Ni plating is usually performed, and in order to bond the Al member, it is also desired to suppress the seizure phenomenon of Ni plating on the covering surface.

An object of the present invention is to provide a Sn-Zn-based solder alloy which can reduce the amount of scum generated even when the molten solder alloy is exposed to the atmosphere, suppress discoloration and re-oxidation of the molten solder alloy, and thereby suppress Al. Or the bite of Ni.

In order to suppress the oxidation of the solder bath, the present inventors have suppressed the formation of an oxide film on the liquid surface of the solder bath by adding oxidation more than Zn to suppress the intrusion of oxygen into the atmosphere. The elements in the tank reduce the amount of scum generated and review it. As a result, the inventors found that by When an element such as Al or Ti which easily forms an oxide film is added to the Sn-Zn solder alloy, an oxide film can be formed on the liquid surface of the solder bath instantaneously, and the oxide film can suppress oxidation of Zn in the solder bath and is apparent. Reduce the effect of the amount of scum. In addition, in order to suppress the erosion of Al and Ni, not only Al is added, but also Ti is added to the Sn-Zn solder alloy at the same time, compared to the soft solder alloy to which only Al is added and only the solder is added with Ti. The alloy was also found to have a better effect than the predicted one. The present inventors have found not only the above results, but also found that the Sn-Zn-Ti-Al solder alloy can suppress discoloration or re-occurrence of oxides after removing scum, and completed the present invention.

Further, the inventors have found that by adding Ni to the Sn-Zn-Ti-Al solder alloy, the effect of suppressing the Ni sebum phenomenon can be further enhanced.

The present invention is as follows.

(1) A solder alloy having an alloy composed of Zn: 3 to 25%, Ti: 0.002 to 0.25%, Al: 0.002 to 0.25%, and the remainder being Sn% by mass.

(2) The alloy composition further contains Ni: 0.005 to 0.3% by mass of the soft solder alloy described in the above (1).

(3) The solder alloy according to the above (1) or (2), which has the alloy composition described above and is used for bonding of Al.

(4) The solder alloy according to the above (1) or (2), which has the alloy composition described above and is used for bonding of Ni.

(5) The above (1) to the above (4) having a mass ratio of 0.4 ≦ Al / (Al + Ti) < 0.6 A solder alloy as described in any of the above.

(6) A solder joint comprising the solder alloy according to any one of the above (1) to (5).

(7) A joining method of the solder alloy according to any one of the above (1) to (5).

1‧‧‧ scum generating device

2‧‧‧Al bite tester

Figure 1 is a schematic view of a dross generating device.

Figure 2 is a schematic diagram of an Al and Ni bite tester.

Figure 3 is a scum weight diagram of a Sn-15Zn-(Ti)-(Al) solder alloy.

Figure 4 is a graph showing the relationship between the weight of scum and the total amount of Ti and Al.

Figure 5 is an Al line break time diagram of a Sn-15Zn-(Ti)-(Al) solder alloy.

Fig. 6 is a graph showing the relationship between the breaking time of Al and the total amount of Al and Ti.

Hereinafter, the present invention will be described in detail. In the present specification, the "%" related to the composition of the solder alloy is not particularly limited to "% by mass".

The Sn-Zn-Ti-Al solder alloy of the present invention reduces the amount of scum generated by containing two elements of Ti and Al. Zn in soft solder alloys is highly active. When Ti or Al is added, an oxide film of Ti or Al is formed on the surface of the solder alloy earlier than the reaction of Zn with oxygen in the atmosphere. As a result, the oxide film suppresses the reaction of oxygen in the atmosphere with Zn in the solder alloy. should. Therefore, in the solder alloy of the present invention, the molten solder alloy in a molten state can reduce the amount of scum generated even when exposed to the atmosphere.

Further, the Sn-Zn-Ti-Al solder alloy of the present invention can suppress the biting phenomenon of Al. In general, the phenomenon of seizure is caused by the mutual diffusion of the elements of the solder alloy and the elements in the joined object, so that the elements in the bonded material are dissolved in the solder joint to be eroded. In order to suppress the biting phenomenon of Al, from the viewpoint of preventing Al from diffusing to Sn, it is not only simply increasing the content of Al, but also suppressing the addition of Sn to the soldering alloy to a diffusion coefficient higher than that of Al. The diffusion of Al into the solder alloy can reduce Al bite. This phenomenon, the higher the melting temperature of the soldering groove, becomes more and more obvious. Further, the Sn-Zn-Ti-Al solder alloy of the present invention can also suppress Ni seizure. From the viewpoint of preventing Ni from diffusing to Sn, it is not only simply increasing the content of Ni, but also suppressing the diffusion of Ni into the solder alloy by adding a Ti having a diffusion coefficient higher than that of Ni to the solder alloy. To reduce Ni seizure.

The alloy composition of the solder alloy of the present invention is as follows.

The content of Zn is 3 to 25%. Zn improves the weldability to Al. When Zn is less than 3%, electrolytic corrosion cannot be suppressed. When the Zn is more than 25%, the melting point of the solder alloy is too high to be handled, resulting in deterioration of workability. The content of Zn is preferably 4 to 23%, more preferably 5 to 20%, and most preferably 12 to 20%.

The content of Ti is 0.002 to 0.25%. Ti not only inhibits the occurrence of scum, but also suppresses the erosion of Al. When the content of Ti is less than 0.002%, the suppression effect of the biting phenomenon of Al cannot be obtained, and it is not included. If Ti is present, the amount of scum may not be suppressed. When Ti is more than 0.25%, the melting point of the solder alloy is high, and an oxide is generated even if the scum is removed. The content of Ti is preferably 0.002 to 0.23%, preferably 0.005 to 0.20%.

The content of Al is 0.002 to 0.25%. Al, the same as Ti, is used to reduce the amount of scum generated and to suppress the erosion of Al. When the content of Al is less than 0.002%, the effect of suppressing the amount of occurrence of scum and the phenomenon of erosion of Al cannot be obtained. Further, the surface of the molten solder alloy in the solder bath is discolored, and the soft solder joint formed by the discolored solder alloy deteriorates in appearance. Moreover, oxides reoccur even if scum is removed. When Al is more than 0.25%, the melting point of the solder alloy is high, and the oxide is regenerated even if the scum is removed. The content of Al is preferably 0.002 to 0.23%, more preferably 0.005 to 0.20%.

The total content of Ti and Al is preferably 0.002 to 0.4%. In this range, it is possible to suppress the rise of the melting point, reduce the amount of scum generated, suppress the occurrence of the erosion of Al or Ni, suppress the discoloration of the appearance, and suppress the recurrence of the oxide after the scum removal. The total content of Ti and Al is preferably 0.004 to 0.4%, more preferably 0.01 to 0.4%.

Further, the mass ratio of Ti and Al is preferably 0.4 ≦ Al / (Al + Ti) < 0.6. When this condition is satisfied, the biting phenomenon of Al can be suppressed in particular. Because the thicker the Al line, the smaller the surface area, the more obvious the inhibition effect of the bite phenomenon. That is, when the Al line is thick, since the time until the Al line is cut is required, the erosion of Al can be prevented. The above ratio is preferably 0.5 ≦ Al / (Al + Ti) < 0.6. Use 0.6 or less as the upper limit because you want to use Ti to get the nick The inhibitory effect of the phenomenon.

The solder alloy of the present invention may further contain Ni. Ni, in addition to suppressing the bite phenomenon of Al, can also suppress the nib phenomenon of Ni when Ni plating is performed on the Al surface. Ni can be further suppressed by adding Ni in the presence of Ti and Al.

The amount of Ni dissolved in the molten solder alloy has its limit. When the solder alloy is made of Ni in advance, the amount of Ni dissolved can be reduced during soldering. Further, since the diffusion coefficient of Ti to Sn is higher than Ni, the amount of Ni dissolved can also be reduced by the addition of Ti. Therefore, by adding Ni, the nib phenomenon of Ni can be suppressed. From such a viewpoint, the content of Ni is preferably 0.005 to 0.3%, and from the viewpoint of suppressing the increase in the melting point of the solder alloy, it is preferably 0.01 to 0.25%.

The solder alloy of the present invention may contain other unavoidable impurities in addition to the aforementioned elements. When it contains unavoidable impurities, of course, it has no effect on the aforementioned effects.

The solder alloy of the present invention is used for fusion welding. For the fusion welding, there is a method (immersion method) in which a static groove for moving the surface of the soft groove is used, and a method (flow method) for using a groove for causing corrugation of the surface of the solder groove.

The solder alloy of the present invention is mainly used for bonding of Al or Ni. For example, it may be used for bonding of elements other than Al or Ni such as a Cu material or a Cu electrode.

The solder alloy of the present invention may be used in the form of a solder bar, a solder ball, an ingot, a wire, or the like. In particular, the solder ball of the present invention is a spherical solder material having a typical diameter of about 0.01 to 1.0 mm. Welding ball, can be general The solder ball manufacturing method is used to manufacture.

In the bonding method using the solder alloy of the present invention, for example, a bonding method in which a solder alloy is melted in a solder bath and a solder is applied to a terminal and immersed in a solder bath can be used. There is no special condition for the joining method of the present invention by using the solder alloy of the present invention. When such joining is performed, the temperature of the molten solder alloy in the solder bath is preferably about 400 °C. The solder alloy of the present invention as shown above is particularly suitable for use in fusion welding.

The solder alloy of the present invention can also be used for the connection of the solder alloy of the present invention to the terminals of the driving components such as transformers, capacitors, coils, and the like. That is, the solder joint of the present invention refers to the joint portion of the terminal and the consumable material as described above. Therefore, the soft solder joint of the present invention can be formed using general soldering conditions as described above.

Further, the solder alloy of the present invention is produced by using a high-purity material or a low-α line material, that is, a low-α-line solder alloy. When the solder alloy is used for bonding between terminals such as the periphery of a memory, softness errors can be prevented.

Example

Using the solder alloy composed of the alloy composition shown in Table 1, the Al wire break time (seconds), the dross weight (g) measurement, the discoloration evaluation of the molten solder alloy, the reoxidation inhibition evaluation, and Determination of the Ni line disconnection time (seconds). Each evaluation method is as shown in the following description.

(1) Determination of scum weight

Fig. 1 is a schematic view of a dross generating device 1 used for the purpose of measuring the weight of dross. To the solder tank 12 having a volume of 150 cc which can be heated by the heater 11, 1000 g of a solder alloy was introduced. The solder alloy is heated by the temperature sensor 14 so that the temperature of the solder alloy introduced into the solder bath 12 is 400 ° C. It is melted and used as a soldering groove 13. Thereafter, the gas introduction tube 15 was used to blow the atmosphere in the soldering bath 13 for 10 minutes at 150 cc/min. After the end of the blowing, the dross formed on the surface of the soldering groove 13 was taken and the weight was measured. In the present embodiment, those having a scum weight of 30 g or less are regarded as having no practical problem. Further, the alloy composition of the solder bath 13 is as shown in Table 1, and the above evaluation was performed for each alloy composition. The results are shown in Table 1.

(2) Determination of the disconnection time of the Al wire

Fig. 2 is a schematic view showing an Al and Ni bite tester 2 used for the purpose of measuring the breakage time of the Al wire and the wire breakage time of the Ni wire. After coating a 0.4 mm-diameter Al wire 21 with a flux (manufactured by Senju Metal Industry Co., Ltd.: Alphlux No. 2A), one end of the Al wire 21 is fixed to the fixing column 22, and the other end is coupled to the hammer 23 and The pillars 24 are supported. In the same manner as in the first embodiment, after the solder alloy is placed in the solder bath 12, it is melted at 400 ° C as a solder bath 13 , and the Al solder wire 21 is pressed from the top to the bottom by the dipping jig 25 to impregnate the Al wire 21 . At a depth of 5 mm from the surface of the solder bath 13. The time from the start of the immersion to the disconnection of the Al wire 21 (the hammer 23 is dropped) is measured. Repeat the same test 5 times and find the line until the Al wire is broken. The average of the time. In the present embodiment, a person who has an Al line disconnection time of 50 seconds or more is regarded as having no problem in practical use. Further, the alloy composition of the solder bath 13 is as shown in Table 1, and the above evaluation was performed for each alloy composition. The results are shown in Table 1.

(3) Evaluation of discoloration

In the solder material bath 12 shown in Fig. 1, the solder alloy was melted at 400 ° C to visually observe the degree of discoloration of the liquid surface of the solder bath 13 . In this embodiment, it is considered that there is no problem in practical use when there is no discoloration. The results are shown in Table 1.

(4) Reoxidation inhibition assessment

After the scum was taken in (1), the solder bath 13 was placed in the air at 400 ° C for 10 minutes to visually observe the extent to which the surface of the solder bath 13 was re-oxidized. The evaluation is carried out on the basis of the following criteria. In the present embodiment, ◎ is a degree that is practically not problematic. The results are shown in Table 1.

◎: No recurrence of oxides was found.

○: A little re-occurrence of oxides was found

×: Obviously found that oxides reoccur

As shown in Table 1, each of the alloy compositions of Examples 1 to 10 exhibited practically no problem.

In Comparative Examples 1 to 3, which did not contain Ti and Al, the scum had a large weight, and it was found that the surface of the solder bath was discolored, and the reoxidation inhibition evaluation was "x". not In Comparative Example 4 containing Al, discoloration was observed, and the reoxidation inhibition evaluation was "○", which was a practically problematic result. In Comparative Example 5, which did not contain Ti, the result that the Al wire break time was short. In Comparative Example 6, which did not contain Ti and Al and contained only Ni, the scum had a large weight, and discoloration was observed, and the reoxidation inhibition evaluation was "x". In Comparative Example 7, in which the content of Ti and Al was small, the Al wire breakage time, scum weight, discoloration, and reoxidation inhibition evaluation all showed practically problematic results. In Comparative Example 8 in which the content of Ti and Al was large, the melting point was high, and the reoxidation inhibition evaluation was "○", which was a practically problematic result.

The results of Table 1 will be further explained based on the effects of the present invention in accordance with Figs. 3 to 5 .

Figure 3 is a scum weight diagram of a Sn-15Zn-(Ti)-(Al) solder alloy. As can be seen from Fig. 3, the addition of Al (and Ti) to the Sn-Zn solder alloy can greatly suppress the scum weight.

Figure 4 is a graph showing the relationship between the weight of scum and the total amount of Ti and Al. As can be seen from Fig. 4, the content of Ti and Al is 0.01% or more, and the weight of the scum is rapidly decreased, and thereafter, the weight of the scum is the same. Further, Examples 8 to 10 containing Ni exhibited the same degree of scum weight as in Examples 1 to 7 which did not contain Ni.

Figure 5 is an Al line break time diagram of a Sn-15Zn-(Ti)-(Al) solder alloy. It can be seen from Fig. 5 that when Ti or Al is added to the Sn-Zn solder alloy, the breaking time of the Al wire becomes long, and when Ti and Al are added, the breaking time of the Al wire is further extended.

Figure 6 shows the relationship between the time of disconnection of Al and the total measurement of Al and Ti. Figure. It can be seen from Fig. 6 that as the content of Ti and Al increases, the line break time of the Al line also increases. It should be an increase in the content of Ti and Al, which inhibits the phenomenon of Al seizure. Further, in Examples 8 to 10 containing Ni, the Al wire breakage time was the same as that of Examples 1 to 7 which did not contain Ni.

Further, in the fourth and sixth figures, in view of the scum weight and the Al wire breakage time, Comparative Example 8 in which Ti (0.3%) + Al (0.3%) = 0.6 is the most excellent. However, as shown in Table 1, the alloy composition, because a small amount of oxide reoccurred, could not satisfy all the evaluation items reviewed in the present embodiment.

(5) Determination of the time of disconnection of Ni wire

In the present embodiment, in order to evaluate the suppression effect of the Ni sebow phenomenon, the average value of the time until the disconnection of the Ni wire is obtained is the same as the measurement of the disconnection time of the (2) Al wire, except for the Ni wire having a diameter of 0.1 mm. . The disconnection time of the Ni wire is 240 seconds or more, which is regarded as practically no problem. The results are shown in Table 2.

In Example 4, which did not contain Ni, and Example 8, which contained Ni, the Ni wire breakage time showed a result of more than 240 seconds. In particular, in Example 8 containing Ni, the Ni wire was broken for a long time, and Ni seizure was more suppressed. In Comparative Example 2, which did not contain Ti, Al, and Ni, the Ni wire was immediately broken. It can be known that the solder alloy of the present invention can suppress the phenomenon of seizure for Ni.

As described above, the solder alloy of the present invention is suitably used for welding a terminal of an axial type electronic component such as a motor or a circuit for Al with a molten solder material. When soldering with molten solder, the solder bath of the solder bath is exposed to the atmosphere. Even in such a use environment, the solder alloy of the present invention can suppress the occurrence of scum and suppress the biting of Al or Ni. The etch phenomenon does not cause discoloration upon melting, and it can also suppress reoxidation after scum removal. In other words, for example, when the Al terminal of the electronic component is immersed in the solder bath or the Al wiring of the circuit is performed by the flow method, it is particularly effective when the molten solder alloy is exposed to the atmosphere.

1‧‧‧ scum generating device

11‧‧‧heater

12‧‧‧welding trough

13‧‧‧Soft solder bath

14‧‧‧Temperature Sensor

15‧‧‧ gas introduction tube

Claims (7)

A solder alloy characterized by having an alloy composition consisting of Zn: 3 to 25%, Ti: 0.002 to 0.25%, Al: 0.002 to 0.25%, and the remainder being Sn% by mass. The solder alloy according to claim 1, wherein the alloy composition further contains Ni: 0.005 to 0.3% by mass. A solder alloy according to claim 1 or 2, which has the alloy composition described above and is used for bonding of Al. A solder alloy according to claim 1 or 2, which has the alloy composition described above and is used for bonding of Ni. The solder alloy according to any one of claims 1 to 4, wherein the mass ratio is 0.4 ≦ Al / (Al + Ti) < 0.6. A soft soldering tip comprising the soft solder alloy described in any one of claims 1 to 5. A bonding method characterized by using the solder alloy according to any one of claims 1 to 5.